/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *
 *    https://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an
 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *  KIND, either express or implied.  See the License for the
 *  specific language governing permissions and limitations
 *  under the License.
 */

package org.grails.datastore.mapping.model;

/**
 * Value generation strategies
 *
 * @author Graeme Rocher
 * @since 6.0
 */
public enum ValueGenerator {
    /**
     * Generated natively from the underlying datastore
     */
    NATIVE,

    /**
     * Using an identity column
     */
    IDENTITY,
    /**
     * Generated through assignment
     */
    ASSIGNED,
    /**
     * Generated by the datastore implementation
     */
    GENERATED,
    /**
     * The default generated
     */
    AUTO,
    /**
     * Generated from a sequence
     */
    SEQUENCE,
    /**
     * A generator that uses a HILO algorithm
     */
    HILO,

    /**
     * A generator that uses a sequence and a HILO algorithm
     */
    SEQHILO,
    /**
     * A generator that uses an auto-increment column
     */
    INCREMENT,
    /**
     * A generator that uses UUIDs
     */
    UUID,
    /**
     * A generator that uses UUID2s
     */
    UUID2,
    /**
     * uses a database-generated GUID string on MS SQL Server and MySQL.
     */
    GUID,
    /**
     * use the identifier of another object
     */
    FOREIGN,
    /**
     * Generates the id by selecting from a row using a unique key
     */
    SELECT,
    /**
     * Custom value generation strategy
     */
    CUSTOM

}
